netdev - Re: [PATCH 1/2] Revert "xfrm: interface with if

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 1 Mar 2022 16:34:52 +0200
From:   Eyal Birger <eyal.birger@...il.com>
To:     Kai Lüke <kailueke@...ux.microsoft.com>
Cc:     netdev@...r.kernel.org,
        Steffen Klassert <steffen.klassert@...unet.com>
Subject: Re: [PATCH 1/2] Revert "xfrm: interface with if_id 0 should return error"

Hi Kai,

On Tue, Mar 1, 2022 at 4:17 PM Kai Lüke <kailueke@...ux.microsoft.com> wrote:
>
> Hi,
> > Whereas 8dce43919566 ("xfrm: interface with if_id 0 should return error")
> > involves xfrm interfaces which don't appear in the pull request.
> >
> > In which case, why should that commit be reverted?
>
> Correct me if I misunderstood this but reading the commit message it is
> explicitly labeled as a behavior change for userspace:
>
>     With this commit:
>      ip link add ipsec0  type xfrm dev lo  if_id 0
>      Error: if_id must be non zero.
>
> Changing behavior this way is from my understanding a regression because
> it breaks programs that happened to work before, even if they worked
> incorrect (cf. https://lwn.net/Articles/726021/ "The current process for
> Linux development says that kernel patches cannot break programs that
> rely on the ABI. That means a program that runs on the 4.0 kernel should
> be able to run on the 5.0 kernel, Levin said.").

Well to some extent, but the point was that xfrm interfaces with if_id=0
were already broken, so returning an error to userspace in such case
would be a better behavior.
So I'm not sure this is a regression but it's not up to me to decide these
things.

Eyal